Network+ PBQ 4: Troubleshooting & Security Controls

Scenario

A network technician is troubleshooting several tickets. One user cannot reach the default gateway. Another switch port shows CRC errors and drops. Voice calls have jitter. Security reports a rogue device and an unused conference-room switch port is active.

Your task: Pick the best tool, protocol, or defense for each issue.

1. First command to test basic IP reachability to gateway:

2. Best command/tool to view path taken across routers:

3. Best command/tool to test DNS resolution:

4. Switch port has CRC errors/drops. Most likely category:

Performance and Security

5. Voice calls have jitter and latency. Best network feature to prioritize voice:

6. Need packet-level evidence from a mirrored switch port. Best tool:

7. Best control for an unused active switch port:

8. Best network access control method to authenticate devices/users on switch ports:

Instructor Answer

ping tests basic reachability.
traceroute/tracert shows the Layer 3 path.
nslookup or dig tests DNS name resolution.
CRC errors and drops commonly point to cabling, interference, duplex/speed, or physical interface problems.
QoS can prioritize voice traffic to reduce jitter impact.
A protocol analyzer/packet capture is used for packet-level analysis.
Unused switch ports should be disabled as part of hardening.
802.1X provides port-based network access control.